What is a chemical stress test, also known as a pharmacological stress test (PST)?

From the Guidelines

A chemical stress test is the preferred diagnostic procedure for patients who are unable to perform physical exercise, particularly those with physical limitations, orthopedic problems, or those who are elderly or debilitated, as it allows for the evaluation of heart function and detection of myocardial ischemia through changes in the electrocardiographic and hemodynamic response 1. When considering a chemical stress test, it is essential to choose the most appropriate stress agent based on the patient's medical history and current condition. For example, regadenoson has a more favorable side-effect profile and appears safe for use in patients with bronchospasm, while dobutamine should be avoided in patients with serious arrhythmias or severe hypertension 1. Some key points to consider when performing a chemical stress test include:

• Administering the stress agent, such as adenosine or regadenoson, according to the standard protocol
• Monitoring the patient's heart rate, blood pressure, ECG, and symptoms during the test
• Using imaging with either nuclear tracers or echocardiography to assess blood flow and heart function
• Avoiding caffeine for 24 hours before the test to ensure accurate results
• Being aware of potential temporary side effects, such as chest discomfort, shortness of breath, or headache, during the procedure In patients with left bundle-branch block, exercise MPI has an unacceptably low specificity, and pharmacological stress MPI, particularly with adenosine, dipyridamole, or regadenoson, is suggested over exercise stress imaging 1. Overall, a chemical stress test is a valuable diagnostic tool for evaluating heart function in patients who cannot perform physical exercise, and its use should be guided by the patient's individual needs and medical history.

From the FDA Drug Label

Regadenoson injection is a pharmacologic stress agent indicated for radionuclide myocardial perfusion imaging (MPI) in patients unable to undergo adequate exercise stress. Adenosine Injection, a pharmacologic stress agent, is indicated as an adjunct to thallium-201 myocardial perfusion scintigraphy in patients unable to exercise adequately

The chemical stress test can be performed using either regadenoson (IV) 2 or adenosine (IV) 3 in patients who are unable to undergo adequate exercise stress.

• Regadenoson (IV) is administered as an intravenous injection within 10 seconds, followed by a 5 mL saline flush, and then the radionuclide myocardial perfusion imaging agent is administered 10–20 seconds after the saline flush.
• Adenosine (IV) is infused over six minutes as a continuous peripheral intravenous infusion. Both agents have similar warnings and precautions, including the risk of myocardial ischemia, cardiac arrest, ventricular arrhythmias, and atrial fibrillation.

From the Research

Chemical Stress Test Overview

• A chemical stress test, also known as a pharmacological stress test, is a medical procedure used to evaluate the heart's function under stress.
• The test involves the use of a medication that increases blood flow to the heart, mimicking the effects of exercise.

Regadenoson as a Stress Agent

• Regadenoson is a pharmacological stress agent that has been widely used since its approval by the Food and Drug Administration (FDA) in 2008 4.
• It is a selective A(2A) adenosine receptor agonist, which means it targets specific receptors in the heart to increase blood flow 5.
• Regadenoson has been shown to be safe and well-tolerated, with fewer side effects compared to other stress agents such as adenosine and dipyridamole 4, 6, 7.

Clinical Utilities of Regadenoson

• Regadenoson has been documented to be effective in detecting reversible myocardial ischemia, with non-inferiority to adenosine in phase 3 clinical trials 4.
• It has been used in specific patient populations, including those with chronic diseases, and has established safety and efficacy in most patients 4.
• However, there are equivocal results in the literature for other chronic diseases, and further studies are needed to fully understand its clinical utilities 4.

Combination with Exercise

• Regadenoson can be combined with low-level treadmill testing or isometric exercise to improve the side effect profile and provide better image quality 6, 8.
• The addition of handgrip exercise to regadenoson administration has been shown to be a well-tolerated and easy method, without loss of time 8.
• This combination has been found to reduce the frequency of side effects and improve image quality compared to regadenoson alone 8.